A Guide to Rainwater Drainage

Posted by david.luukas

Jan30

Heavy rain is not an uncommon occurrence in the UK. On average, the UK sees 750mm of rainfall every year. This heavy rainfall can cause considerable amounts of damage to homes that aren’t properly maintained.

It’s vital that you are familiar with your home’s drainage, guttering and downpipes, and are able to spot problems when they occur. This will enable you to fix any damage and replace broken parts, preventing further damage to your home from heavy rainfall.

Guttering and Downpipes

Your guttering is one of the most important parts of your rainwater drainage system. It provides the first line of defence against rainfall. Rainwater guttering catches water as it drains of your roof. The guttering then directs the water towards rainwater downpipes, taking it away from your home.

On average, a home should have gutters that are at least 100mm wide. This should be large enough to cope with a heavy downpour. However, homes that have roofs with a large surface area, or homes in areas when rainfall is particularly heavy, may need larger gutters to cope with the increased amount of water.

For guttering with a width of around 100mm, downpipes should be around 75mm wide.

Take the time to check your guttering and downpipes regularly, particularly if it has been raining heavily.

If water begins leaking over the edge of your guttering or at the joint where two pieces of guttering connect, it indicates that there may be a blockage in your drainage system. This is usually caused by overhanging trees of plants.

If you suspect there is a blockage in your guttering, you should remove is as soon as you can. If the blockage has caused damage to your guttering or downpipes, part of them may need to be replaced.

Gutter Outlets and Gullies

The gutter outlet feeds rainwater directly into your downpipes. They are usually straight, although homes with overhanging eaves may require a gutter outlet with a double bend called a ‘swan neck’.

The gully is a ground-level drain into which your downpipes directs rainwater. Most gullies also have an underground u-bend. This is used to catch smells and stop them escaping up the downpipe.

It’s very common for gullies to get blocked with leaves over the autumn and winter months. Your gully should be cleaned regularly to prevent a serious blockage from building up. If your gully stops working as it should, you may have an obstruction that should be removed with an auger.

Which Material?

Most modern houses are fitted with PVCu guttering, while many older homes have cast iron gutters. Both systems have similar components, consisting of sections of guttering, a gutter outlet and a downpipe.

In general, cast iron guttering needs more maintenance that its PVCu counterpart. However, cast iron components usually look more appropriate on older properties. The guttering can also be painted any colour you wish. Another option is aluminium guttering. While more expensive than PVCu and aluminium, it is generally more hardwearing and requires less maintenance.